Method and apparatus for an adjustable damper

ABSTRACT

An air bleed system for a suspension fork or shock absorber includes: a fluid passage between an interior of the suspension and an exterior of the suspension; and a manually operable valve having a first position substantially closing the fluid passage and a second position allowing fluid flow between the interior and the exterior.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and claims priority of co-pendingU.S. provisional patent application Ser. No. 61/644,859, filed on May 9,2012, entitled “METHODS AND APPARATUS FOR PRESSURE EQUALIZATION” byWilliam H. Becker, assigned to the assignee of the present application,having Attorney Docket No. FOX-P5-08-12.PRO, and is hereby incorporatedby reference in its entirety herein.

BACKGROUND

1. Field of the Invention

Embodiments of the invention generally relate to methods and apparatusesfor use in suspension components. Particular embodiments of theinvention relate to method and apparatus useful for equalizing ambientpressure within vehicle suspension.

2. Description of the Related Art

Vehicle suspension systems typically include a spring component orcomponents and a dampening component or components. Typically,mechanical springs, like helical springs are used with some type ofviscous fluid-based dampening mechanism and the two are mountedfunctionally in parallel. In some instances, a spring may comprisepressurized gas and features of the damper or spring areuser-adjustable, such as by adjusting the air pressure in a gas spring.A damper may be constructed by placing a damping piston in afluid-filled cylinder (e.g., liquid such as oil). As the damping pistonis moved in the cylinder, fluid is compressed and passes from one sideof the piston to the other side. Often, the piston includes ventsthere-through which may be covered by shim stacks to provide fordifferent operational characteristics in compression or extension.

Ambient air pressure at the time of building a suspension fork is sealedinside the fork legs. When the fork is assembled at low elevation andthen taken to ride at high elevations, the air pressure sealed in thelower leg, because of the decreased high elevation exterior air pressureand corresponding differential pressure, adds pressure and load to theseal, which ultimately creates significantly higher axial friction inthe telescoping suspension fork.

As the foregoing illustrates, what is needed in the art are improvedtechniques for lowering equalizing ambient pressure within a vehiclesuspension.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a front bicycle fork, in accordance with an embodiment.

FIG. 2 depicts a cross-sectional view of the air bleed assembly and thevent hole between the seal and the upper busing, in accordance with anembodiment.

FIG. 3 depicts a perspective view of the air bleed assembly, inaccordance with an embodiment.

FIG. 4 depicts a positioning of the air bleed assembly relative to theoil bath lubrication in the lower leg/shock tube, in accordance with anembodiment.

The drawings referred to in this description should be understood as notbeing drawn to scale except if specifically noted.

BRIEF DESCRIPTION

Reference will now be made in detail to embodiments of the presenttechnology, examples of which are illustrated in the accompanyingdrawings. While the technology will be described in conjunction withvarious embodiment(s), it will be understood that they are not intendedto limit the present technology to these embodiments. On the contrary,the present technology is applicable to alternative embodiments,modifications and equivalents, which may be included within the spiritand scope of the invention as defined by the appended claims.

One embodiment hereof comprises a shock absorber for a vehicle. In oneembodiment, the vehicle is a bicycle. The shock absorber, for example, afront fork 100 as shown in FIG. 1, is advantageous because it includes adamper 118/114 (lower fork tube and upper fork tube, respectively, ofthe damper leg) having a manually adjustable damping resistance. In oneembodiment, the manually adjustable damping function allows a user toadjust a “platform” threshold which must be exceeded before the shockabsorber can experience significant compression travel. It allows theuser to establish a level, in one embodiment, for compression dampingwhereby such damping is increased or decreased selectively.

U.S. Pat. No. 6,135,434, which patent is herein incorporated byreference in its entirety, shows certain variations of positive andnegative spring mechanisms. Another selectively variable dampingmechanism is shown in U.S. Pat. No. 6,360,857, which patent is hereinincorporated by reference in its entirety. Optionally, any of theforegoing mechanisms may be integrated, or used in combination, with anyother features disclosed herein.

U.S. Pat. Nos. 6,415,895, 6,296,092, 6,978,872 and 7,308,976, each ofwhich patents is herein incorporated by reference in its entirety, showcertain variations of position sensitive damping mechanisms. Anotherposition sensitive damping mechanism is shown in U.S. Pat. No.7,374,028, which patent is herein incorporated by reference in itsentirety. Another position sensitive damping mechanism is shown in U.S.Pat. No. 5,190,126, which patent is herein incorporated by reference inits entirety. Optionally, any of the foregoing mechanisms may beintegrated, or used in combination, with any other features disclosedherein.

U.S. Pat. Nos. 6,581,948, 7,273,137, 7,261,194, 7,128,192, and6,604,751, each of which patents is herein incorporated by reference inits entirety, show certain variations of inertia valve mechanisms forcontrolling aspects of compression damping. Additionally, U.S. Publishedpatent Application Nos. 2008/0053768 A1, 2008/0053767 A1, 2008/0035439A1, 2008/0007017 A1, 2007/0296163 A1, 2007/0262555 A1, 2007/0228691 A1,2007/0228690 A1, 2007/0227845 A1, 2007/0227844 A1, 2007/0158927 A1,2007/0119670 A1, 2007/0068751 A1, 2007/0012531 A1, 2006/0065496 A1, eachof which patent applications is herein incorporated by reference in itsentirety, show certain variations of inertia valve mechanisms forcontrolling aspects of compression damping. Optionally, any of theforegoing inertia valve mechanisms or other features may be integrated,or used in combination, with any other features disclosed herein. Ashock absorber or fork may be equipped, for example, with an inertiavalve for controlling an aspect of damping and a position sensitivevalve for controlling another aspect of damping.

FIG. 1, FIG. 3, and FIG. 4, show suspension fork legs, either or both ofwhich would, in one embodiment, comprise portions of a bicycle fork (ormotorcycle fork). During operation, the damper leg of the fork issubject to compression and rebound loads. The compression is induced bydisparities in the terrain being traversed by a vehicle equipped withthe fork. The rebound is induced by a spring (e.g. gas spring,mechanical spring, coil—not shown but for example in leg 104/108),preferably located in another leg of the fork, which stores energyduring compression of the fork and then releases that energy when thedisparity is passed. The energy is released in urging the suspensionunit to elongate axially following the axial compression during whichthe energy is stored. The top cap 103 and its connected parts move withthe upper fork tube 114 and 108 during compression and rebound and thelower nut assembly 101 and its connected parts move with the lower forktube 104 or 118.

Movement of the upper fork tube (e.g., 114) relative to the lower forktube (e.g., 118) causes a piston assembly to move axially within thedamper body. During a compression stroke, the piston assembly movesdownward in the damper body and thereby reduces the volume of thecompression chamber. As fluid is displaced from the compression chamber,some of it flows through passages and deflects a one way shim valve toenter the rebound chamber. Some of the displaced fluid flows through anorifice into a reservoir. The resistance to movement of fluid from thecompression chamber, through passages (and shim valve on piston) and theorifice provide compression damping for the suspension unit in which thedamper cartridge is included.

Ambient air pressure at the time of building a suspension fork is“sealed” inside the upper leg/lower leg assembly (e.g., upper fork tube114 telescopically positioned within lower fork tube 118). In oneembodiment, it is preferred that the air pressure within the assembly atstatic (unloaded) extension be substantially equal to ambient exteriorair pressure so that there is no net differential pressure acting acrossthe lower leg seal 135 (see FIG. 3). Suspension forks are often riddenat many different elevations, however, and the ambient air pressurereduces (decreases) as a function of increasing elevation (and increasesat lower elevations).

Air pressure above sea level can be calculated as:

P=1091325(1-2.2577 10⁻⁵ h)^(5.25588)

Where p=pressure absolute and h=altitude above sea level.

The typical ambient air pressure at 8,000 ft. elevation is 3.80 psilower than the trapped air pressure inside the fork. The typical ambientair pressure at 10,000 ft. elevation is 4.60 psi lower than the trappedair pressure inside the fork.(http://www.engineeringtoolbox.com/air-altitude-pressure-d462.html.)

When a fork is assembled at low elevation and then taken to ride at highelevations, the “sealed lower leg air pressure”, because of the nowdecreased high elevation exterior air pressure and correspondingdifferential pressure, adds pressure and load to the lower oil controllip of the seal which creates significantly higher axial friction in atelescoping suspension fork.

The presently disclosed system allows a rider to push a button and letthe pressure in the lower leg equalize to ambient pressure at highelevation and therefore restore a lower-friction fork. Generally, it isimportant to seal a fork to prevent the lower leg oil bath lubricationfrom leaking out of the fork. In one embodiment, the air bleed assembly300 (of FIG. 4) is located right below the lower leg seal 135 so thatwhen excessive air pressure in the fork is relieved at high elevation,the oil bath 140 typically leveled in the lower leg (typically 20-50 cc)does not spray/leak out. In other words, a substantial portion (most ofthe oil bath 140), if not all, of the oil bath 140 remains within thelower leg (and does not spray/leak out of the lower leg) when the airbleed assembly 300 is opened to release excessive air pressure from thefork.

FIG. 3 shows the air bleed assembly 300 including button 150 positionedon a die-cast feature of the lower leg. Pressing the button 150equalizes the air pressure in the fork/shock assembly with the localambient air pressure.

FIG. 2 shows a cross-section of the air bleed assembly 300 and the venthole 154 between the seal (not shown) and the upper bushing 120 (orbehind foam ring 125). When the button 150 is pressed, the sealingo-ring 151 moves into the diametrical recess 152 and thereby becomesunsealed, letting the air pressure by-pass into or out of the fork legvia vent hole 154 to equalize the pressure in the fork leg with anexterior pressure. When the button 150 is released, a spring 153, whichbiases the button/valve 150 toward a closed position, urges the o-ring151 into a sealing engagement with a seal bore 155.

FIG. 4 shows positioning of the air bleed assembly 300 relative to the“oil bath” lubrication in the lower leg/shock tube.

It should be noted that any of the features disclosed herein may beuseful alone or in any suitable combination. While the foregoing isdirected to embodiments of the present invention, other and furtherembodiments of the invention may be implemented without departing fromthe scope of the invention, and the scope thereof is determined by theclaims that follow.

1. An air bleed system for a suspension fork or shock absorbercomprising: a fluid passage between an interior of the suspension and anexterior of the suspension; and a manually operable valve having a firstposition substantially closing said fluid passage and a second positionallowing a fluid to flow between said interior and said exterior.
 2. Theair bleed system of claim 1, wherein said suspension fork or shockabsorber comprises: a damper.
 3. The air bleed system of claim 1,wherein said fluid comprises: a gas.
 4. The air bleed system of claim 1,wherein said fluid comprises: a liquid.
 5. The air bleed system of claim1, wherein said fluid comprises: a combination of a gas and a liquid. 6.The air bleed system of claim 1, wherein said air bleed system ispositioned at a distance from an oil bath lubrication within saidsuspension fork or shock absorber such that when said manually operablevalve is in said second position, a substantial portion of said oil bathlubrication remains within said suspension fork or shock absorber. 7.The air bleed system of claim 6, wherein said air bleed system ispositioned right below a lower leg seal coupled to a lower leg of saidsuspension fork or shock absorber, such that when excessive air pressurein said suspension fork or shock absorber is relieved at high elevation,said substantial portion of said oil bath lubrication that is leveled insaid lower leg remains within said lower leg.
 8. The air bleed system ofclaim 1, further comprising: a valve activator coupled with saidmanually operable valve, said valve activator comprising: an activationposition configured for, upon activation, positioning said manuallyoperable valve into said first position; and a deactivation positionconfigured for, upon deactivation, positioning said manually operablevalve into said second position, and whereupon said activation, the airpressure in said suspension is equalized with the local ambient airpressure.
 9. The air bleed system of claim 8, wherein said valveactivator comprises: a button configured for being pressed for saidactivation and said deactivation.
 10. The air bleed system of claim 8,wherein said valve activator is positioned on a die-cast feature of saidsuspension.
 11. The air bleed system of claim 10, further comprising: adiametrical recess; and a sealing o-ring comprising: a sealed position;and an unsealed position, wherein said sealed position seals betweensaid die-cast feature and said suspension, whereupon said activation,said sealing o-ring moves into said diametrical recess, therebyattaining said unsealed position and letting air pressure by-pass intoor out of said suspension via a vent hole.
 12. The air bleed system ofclaim 8, wherein said manually operable valve comprises: a springcoupled with said valve activator, whereupon said deactivation, saidspring biases said valve activator toward said first position.
 13. Theair bleed system of claim 12, wherein said second position comprises: asealing engagement between said sealing o-ring and a seal bore, whereinwhen in said sealing engagement, said air pressure does not by-pass intoor out of said suspension.
 14. A fluid equalization system for asuspension fork or shock absorber comprising: a fluid flow path betweena region of said suspension fork or shock absorber having a firstpressure and a region having a second pressure; and a valve memberhaving a first position substantially obstructing said flow path and asecond position wherein said flow path is open.
 15. The fluidequalization system of claim 14, wherein said region of said suspensionfork or shock absorber having said first pressure is one of an interiorof said suspension fork or shock absorber and an exterior of saidsuspension fork or shock absorber.
 16. The fluid equalization system ofclaim 14, wherein said region having said second pressure is one of aninterior of said suspension fork or shock absorber and an exterior ofsaid suspension fork or shock absorber.
 17. The fluid equalizationsystem of claim 14, wherein said first position comprises: a sealingo-ring partially enclosed by a valve activator; and a spring, saidsealing o-ring comprising: a sealed position, wherein when in saidsealed position, said spring biases said valve activator toward a closedposition and said sealing o-ring presses against a sealing bore suchthat air pressure does not pass into or out of said suspension fork orshock absorber.
 18. The fluid equalization system of claim 17, whereinsaid valve activator comprises: a button configured for being pressedfor activation or deactivation.
 19. The fluid equalization system ofclaim 17, wherein said valve activator is positioned on a die-castfeature of said suspension.
 20. The fluid equalization system of claim14, wherein said second position comprises: a diametrical recess; asealing o-ring partially enclosed by a valve activator; and a spring,said sealing o-ring comprising: an unsealed position, wherein when insaid unsealed position, said sealing o-ring moves into said diametricalrecess, thereby letting air pressure by-pass into or out of saidsuspension fork or shock absorber.